Piston Slap: When to Step Away From the Drawing Board?

Sajeev Mehta
by Sajeev Mehta
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piston slap when to step away from the drawing board

TTAC Commentator Arthur Dailey writes (and edited to remove confusion):

Sajeev,

Opening my 2011 Hyundai Sonata’s door this morning after a beautiful overnight snowfall (Yes, it takes that long to answer Piston Slap questions – SM), I once again was confronted with a driver’s seat and inside door panel, covered in snow.

Those living in the snow belt will often park their car at the rink, library, ski hill, mall, at work etc. and return to find it covered in snow. You don’t bring your scraper with you in these situations. And even if you use your glove/arm/hand to clear some of the snow, when you open your door, the residue falls. Onto your power window/mirror/door lock mechanisms. And often onto the seat. You get into your car and start it to warm it up and help clear the windshield. And that residue melts.

This is a re-occurring problem: happening in many other vehicles that I have recently rented/owned. With the sloped roofs now common on cars, snow regularly falls into the passenger compartment when you open the door. There used to be gutters/sills along the edges of car rooflines. In fact I believe that up until the 1960’s they might have been an optional extra, as they were often chromed. Later they were just an integrated part of the roof.

I can’t remember exactly when roofline gutters disappeared from cars, but I understand that this was probably due to aerodynamic issues. I also noticed that there are a number of aftermarket options now available, sometimes referred to as ‘rain guards’.

However why can’t auto designers develop a roofline that prevents snow from dropping onto the car seats whenever the door is opened?

Sajeev answers:

You’ve opened a lot of doors (sorry) with your query!

  1. Rain guards only work when doors are closed, therefore I see no product addressing your concern. Best and Brightest: a little help?
  2. Sloped roofs are usually better for aerodynamics, but the curvature might also improve safety: metallurgy and finite element analysis aside, a curved roof can channel energy better than a boxier one.
  3. You must remove snow before opening the door. Not only does it solve your problem, it’s the law in certain states/provinces.

It’s not just the roof, you’re clearing the snow from the hood and trunk too. All horizontal surfaces, Son!

If your state lacks such a rule, perhaps we need YouTube-guilt you to drive the point home.

Sure, your query coulda been about entering a vehicle to not drive it, but I’m not gonna assume that.

And this isn’t a case of car designers going back to the drawing board, it’s about stepping away from it. Far, far away.

[Image: Shutterstock/Paul Vasarhelyi]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.


Sajeev Mehta
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  • Jeff S Jeff S on Jul 11, 2019

    The window deflectors you can buy online or thru Weathertech are good if you want to crack your windows in the heat and not worry about getting water inside if it rains. Doesn't help with the snow but it works for cracking your windows in the heat.

  • Jeff S Jeff S on Jul 11, 2019

    The first car I bought did not have gutters and every time it rained and you opened the door you would get a lap full of water. That was a 73 Chevelle DeLuxe sedan. I don't remember my 77 Monte Carlo having a real gutter as well. I think my 85 Mitsubishi Mighty Max pickup had gutters. The last time I remember roof gutters being on most vehicles was the early 70s which is about the last time I remember vent windows being on most cars--it took trucks over a decade to start doing away with those things.

  • Carsofchaos The bike lanes aren't even close to carrying "more than the car lanes replaced". You clearly don't drive in Midtown Manhattan on a daily like I do.
  • Carsofchaos The problem with congestion, dear friends, is not the cars per se. I drive into the city daily and the problem is this:Your average street in the area used to be 4 lanes. Now it is a bus lane, a bike lane (now you're down to two lanes), then you have delivery trucks double parking, along with the Uber and Lyft drivers also double parking. So your 4 lane avenue is now a 1.5 lane avenue. Do you now see the problem? Congestion pricing will fix none of these things....what it WILL do is fund persion plans.
  • FreedMike Many F150s I encounter are autonomously driven...and by that I mean they're driving themselves because the dips**ts at the wheel are paying attention to everything else but the road.
  • Tassos A "small car", TIM????????????This is the GLE. Have you even ever SEEN the huge thing at a dealer's??? NOT even the GLC,and Merc has TWO classes even SMALLER than the C (The A and the B, you guessed it? You must be a GENIUS!).THe E is a "MIDSIZED" crossover, NOT A SMALL ONE BY ANY STRETCH OF THE IMAGINATION, oh CLUELESS one.I AM SICK AND TIRED OF THE NONSENSE you post here every god damned day.And I BET you will never even CORRECT your NONSENSE, much less APOLOGIZE for your cluelessness and unprofessionalism.
  • Stuki Moi "How do you take a small crossover and make it better?Slap the AMG badge on it and give it the AMG treatment."No, you don't.In fact, that is specifically what you do NOT do.Huge, frail wheels, and postage stamp sidewalls, do nothing but make overly tall cuvs tramline and judder. And render them even less useful across the few surfaces where they could conceivably have an advantage over more properly dimensioned cars. And: Small cuvs have pitiful enough fuel range as it is, even with more sensible engines.Instead, to make a small CUV better, you 1)make it a lower slung wagon. And only then give it the AMG treatment. AMG'ing, makes sense for the E class. And these days with larger cars, even the C class. For the S class, it never made sense, aside from the sheer aural visceralness of the last NA V8. The E-class is the center of AMG. Even the C-class, rarely touches the M3.Or 2) You give it the Raptor/Baja treatment. Massive, hypersophisticated suspension travel allowing landing meaningful jumps. As well as driving up and down wide enough stairs if desired. That's a kind of driving for which a taller stance, and IFS/IRS, makes sense.Attempting to turn a CUV into some sort of a laptime wonder, makes about as much sense as putting an America's Cup rig atop a ten deck cruiseship.
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